Although psychotherapy and antidepressants seem to help initially, many depressed patients suffer from relapse and recurrence. Recent findings suggest cognitive behaviour therapy (CBT) may reduce that risk in the long-term, but the mechanisms of change that prevent relapse and recurrence are still unknown. We will be the first to study the effectiveness of CBT compared to interpersonal therapy (IPT) for residual depression after initial treatment (reduction of symptoms; prevention of relapse and recurrence) and the underlying mechanisms of change (explicit and implicit measures). Participants will partly be recruited from an ongoing treatment study in primary care. These patients with residual depression will be offered psychotherapy (CBT or IPT) at our clinical site.